summaryrefslogtreecommitdiff
path: root/Lib/test/test_scope.py
blob: b325545f32d0b596847adabc9dd53a1a7b09d9ea (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
import unittest
import weakref

from test.support import check_syntax_error, cpython_only, run_unittest


class ScopeTests(unittest.TestCase):

    def testSimpleNesting(self):

        def make_adder(x):
            def adder(y):
                return x + y
            return adder

        inc = make_adder(1)
        plus10 = make_adder(10)

        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(-2), 8)

    def testExtraNesting(self):

        def make_adder2(x):
            def extra(): # check freevars passing through non-use scopes
                def adder(y):
                    return x + y
                return adder
            return extra()

        inc = make_adder2(1)
        plus10 = make_adder2(10)

        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(-2), 8)

    def testSimpleAndRebinding(self):

        def make_adder3(x):
            def adder(y):
                return x + y
            x = x + 1 # check tracking of assignment to x in defining scope
            return adder

        inc = make_adder3(0)
        plus10 = make_adder3(9)

        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(-2), 8)

    def testNestingGlobalNoFree(self):

        def make_adder4(): # XXX add exta level of indirection
            def nest():
                def nest():
                    def adder(y):
                        return global_x + y # check that plain old globals work
                    return adder
                return nest()
            return nest()

        global_x = 1
        adder = make_adder4()
        self.assertEqual(adder(1), 2)

        global_x = 10
        self.assertEqual(adder(-2), 8)

    def testNestingThroughClass(self):

        def make_adder5(x):
            class Adder:
                def __call__(self, y):
                    return x + y
            return Adder()

        inc = make_adder5(1)
        plus10 = make_adder5(10)

        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(-2), 8)

    def testNestingPlusFreeRefToGlobal(self):

        def make_adder6(x):
            global global_nest_x
            def adder(y):
                return global_nest_x + y
            global_nest_x = x
            return adder

        inc = make_adder6(1)
        plus10 = make_adder6(10)

        self.assertEqual(inc(1), 11) # there's only one global
        self.assertEqual(plus10(-2), 8)

    def testNearestEnclosingScope(self):

        def f(x):
            def g(y):
                x = 42 # check that this masks binding in f()
                def h(z):
                    return x + z
                return h
            return g(2)

        test_func = f(10)
        self.assertEqual(test_func(5), 47)

    def testMixedFreevarsAndCellvars(self):

        def identity(x):
            return x

        def f(x, y, z):
            def g(a, b, c):
                a = a + x # 3
                def h():
                    # z * (4 + 9)
                    # 3 * 13
                    return identity(z * (b + y))
                y = c + z # 9
                return h
            return g

        g = f(1, 2, 3)
        h = g(2, 4, 6)
        self.assertEqual(h(), 39)

    def testFreeVarInMethod(self):

        def test():
            method_and_var = "var"
            class Test:
                def method_and_var(self):
                    return "method"
                def test(self):
                    return method_and_var
                def actual_global(self):
                    return str("global")
                def str(self):
                    return str(self)
            return Test()

        t = test()
        self.assertEqual(t.test(), "var")
        self.assertEqual(t.method_and_var(), "method")
        self.assertEqual(t.actual_global(), "global")

        method_and_var = "var"
        class Test:
            # this class is not nested, so the rules are different
            def method_and_var(self):
                return "method"
            def test(self):
                return method_and_var
            def actual_global(self):
                return str("global")
            def str(self):
                return str(self)

        t = Test()
        self.assertEqual(t.test(), "var")
        self.assertEqual(t.method_and_var(), "method")
        self.assertEqual(t.actual_global(), "global")

    def testCellIsKwonlyArg(self):
        # Issue 1409: Initialisation of a cell value,
        # when it comes from a keyword-only parameter
        def foo(*, a=17):
            def bar():
                return a + 5
            return bar() + 3

        self.assertEqual(foo(a=42), 50)
        self.assertEqual(foo(), 25)

    def testRecursion(self):

        def f(x):
            def fact(n):
                if n == 0:
                    return 1
                else:
                    return n * fact(n - 1)
            if x >= 0:
                return fact(x)
            else:
                raise ValueError("x must be >= 0")

        self.assertEqual(f(6), 720)


    def testUnoptimizedNamespaces(self):

        check_syntax_error(self, """if 1:
            def unoptimized_clash1(strip):
                def f(s):
                    from sys import *
                    return getrefcount(s) # ambiguity: free or local
                return f
            """)

        check_syntax_error(self, """if 1:
            def unoptimized_clash2():
                from sys import *
                def f(s):
                    return getrefcount(s) # ambiguity: global or local
                return f
            """)

        check_syntax_error(self, """if 1:
            def unoptimized_clash2():
                from sys import *
                def g():
                    def f(s):
                        return getrefcount(s) # ambiguity: global or local
                    return f
            """)

        check_syntax_error(self, """if 1:
            def f():
                def g():
                    from sys import *
                    return getrefcount # global or local?
            """)

    def testLambdas(self):

        f1 = lambda x: lambda y: x + y
        inc = f1(1)
        plus10 = f1(10)
        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(5), 15)

        f2 = lambda x: (lambda : lambda y: x + y)()
        inc = f2(1)
        plus10 = f2(10)
        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(5), 15)

        f3 = lambda x: lambda y: global_x + y
        global_x = 1
        inc = f3(None)
        self.assertEqual(inc(2), 3)

        f8 = lambda x, y, z: lambda a, b, c: lambda : z * (b + y)
        g = f8(1, 2, 3)
        h = g(2, 4, 6)
        self.assertEqual(h(), 18)

    def testUnboundLocal(self):

        def errorInOuter():
            print(y)
            def inner():
                return y
            y = 1

        def errorInInner():
            def inner():
                return y
            inner()
            y = 1

        self.assertRaises(UnboundLocalError, errorInOuter)
        self.assertRaises(NameError, errorInInner)

    def testUnboundLocal_AfterDel(self):
        # #4617: It is now legal to delete a cell variable.
        # The following functions must obviously compile,
        # and give the correct error when accessing the deleted name.
        def errorInOuter():
            y = 1
            del y
            print(y)
            def inner():
                return y

        def errorInInner():
            def inner():
                return y
            y = 1
            del y
            inner()

        self.assertRaises(UnboundLocalError, errorInOuter)
        self.assertRaises(NameError, errorInInner)

    def testUnboundLocal_AugAssign(self):
        # test for bug #1501934: incorrect LOAD/STORE_GLOBAL generation
        exec("""if 1:
            global_x = 1
            def f():
                global_x += 1
            try:
                f()
            except UnboundLocalError:
                pass
            else:
                fail('scope of global_x not correctly determined')
            """, {'fail': self.fail})

    def testComplexDefinitions(self):

        def makeReturner(*lst):
            def returner():
                return lst
            return returner

        self.assertEqual(makeReturner(1,2,3)(), (1,2,3))

        def makeReturner2(**kwargs):
            def returner():
                return kwargs
            return returner

        self.assertEqual(makeReturner2(a=11)()['a'], 11)

    def testScopeOfGlobalStmt(self):
        # Examples posted by Samuele Pedroni to python-dev on 3/1/2001

        exec("""if 1:
            # I
            x = 7
            def f():
                x = 1
                def g():
                    global x
                    def i():
                        def h():
                            return x
                        return h()
                    return i()
                return g()
            self.assertEqual(f(), 7)
            self.assertEqual(x, 7)

            # II
            x = 7
            def f():
                x = 1
                def g():
                    x = 2
                    def i():
                        def h():
                            return x
                        return h()
                    return i()
                return g()
            self.assertEqual(f(), 2)
            self.assertEqual(x, 7)

            # III
            x = 7
            def f():
                x = 1
                def g():
                    global x
                    x = 2
                    def i():
                        def h():
                            return x
                        return h()
                    return i()
                return g()
            self.assertEqual(f(), 2)
            self.assertEqual(x, 2)

            # IV
            x = 7
            def f():
                x = 3
                def g():
                    global x
                    x = 2
                    def i():
                        def h():
                            return x
                        return h()
                    return i()
                return g()
            self.assertEqual(f(), 2)
            self.assertEqual(x, 2)

            # XXX what about global statements in class blocks?
            # do they affect methods?

            x = 12
            class Global:
                global x
                x = 13
                def set(self, val):
                    x = val
                def get(self):
                    return x

            g = Global()
            self.assertEqual(g.get(), 13)
            g.set(15)
            self.assertEqual(g.get(), 13)
            """)

    def testLeaks(self):

        class Foo:
            count = 0

            def __init__(self):
                Foo.count += 1

            def __del__(self):
                Foo.count -= 1

        def f1():
            x = Foo()
            def f2():
                return x
            f2()

        for i in range(100):
            f1()

        self.assertEqual(Foo.count, 0)

    def testClassAndGlobal(self):

        exec("""if 1:
            def test(x):
                class Foo:
                    global x
                    def __call__(self, y):
                        return x + y
                return Foo()

            x = 0
            self.assertEqual(test(6)(2), 8)
            x = -1
            self.assertEqual(test(3)(2), 5)

            looked_up_by_load_name = False
            class X:
                # Implicit globals inside classes are be looked up by LOAD_NAME, not
                # LOAD_GLOBAL.
                locals()['looked_up_by_load_name'] = True
                passed = looked_up_by_load_name

            self.assertTrue(X.passed)
            """)

    def testLocalsFunction(self):

        def f(x):
            def g(y):
                def h(z):
                    return y + z
                w = x + y
                y += 3
                return locals()
            return g

        d = f(2)(4)
        self.assertIn('h', d)
        del d['h']
        self.assertEqual(d, {'x': 2, 'y': 7, 'w': 6})

    def testLocalsClass(self):
        # This test verifies that calling locals() does not pollute
        # the local namespace of the class with free variables.  Old
        # versions of Python had a bug, where a free variable being
        # passed through a class namespace would be inserted into
        # locals() by locals() or exec or a trace function.
        #
        # The real bug lies in frame code that copies variables
        # between fast locals and the locals dict, e.g. when executing
        # a trace function.

        def f(x):
            class C:
                x = 12
                def m(self):
                    return x
                locals()
            return C

        self.assertEqual(f(1).x, 12)

        def f(x):
            class C:
                y = x
                def m(self):
                    return x
                z = list(locals())
            return C

        varnames = f(1).z
        self.assertNotIn("x", varnames)
        self.assertIn("y", varnames)

    @cpython_only
    def testLocalsClass_WithTrace(self):
        # Issue23728: after the trace function returns, the locals()
        # dictionary is used to update all variables, this used to
        # include free variables. But in class statements, free
        # variables are not inserted...
        import sys
        self.addCleanup(sys.settrace, sys.gettrace())
        sys.settrace(lambda a,b,c:None)
        x = 12

        class C:
            def f(self):
                return x

        self.assertEqual(x, 12) # Used to raise UnboundLocalError

    def testBoundAndFree(self):
        # var is bound and free in class

        def f(x):
            class C:
                def m(self):
                    return x
                a = x
            return C

        inst = f(3)()
        self.assertEqual(inst.a, inst.m())

    @cpython_only
    def testInteractionWithTraceFunc(self):

        import sys
        def tracer(a,b,c):
            return tracer

        def adaptgetter(name, klass, getter):
            kind, des = getter
            if kind == 1:       # AV happens when stepping from this line to next
                if des == "":
                    des = "_%s__%s" % (klass.__name__, name)
                return lambda obj: getattr(obj, des)

        class TestClass:
            pass

        self.addCleanup(sys.settrace, sys.gettrace())
        sys.settrace(tracer)
        adaptgetter("foo", TestClass, (1, ""))
        sys.settrace(None)

        self.assertRaises(TypeError, sys.settrace)

    def testEvalExecFreeVars(self):

        def f(x):
            return lambda: x + 1

        g = f(3)
        self.assertRaises(TypeError, eval, g.__code__)

        try:
            exec(g.__code__, {})
        except TypeError:
            pass
        else:
            self.fail("exec should have failed, because code contained free vars")

    def testListCompLocalVars(self):

        try:
            print(bad)
        except NameError:
            pass
        else:
            print("bad should not be defined")

        def x():
            [bad for s in 'a b' for bad in s.split()]

        x()
        try:
            print(bad)
        except NameError:
            pass

    def testEvalFreeVars(self):

        def f(x):
            def g():
                x
                eval("x + 1")
            return g

        f(4)()

    def testFreeingCell(self):
        # Test what happens when a finalizer accesses
        # the cell where the object was stored.
        class Special:
            def __del__(self):
                nestedcell_get()

    def testNonLocalFunction(self):

        def f(x):
            def inc():
                nonlocal x
                x += 1
                return x
            def dec():
                nonlocal x
                x -= 1
                return x
            return inc, dec

        inc, dec = f(0)
        self.assertEqual(inc(), 1)
        self.assertEqual(inc(), 2)
        self.assertEqual(dec(), 1)
        self.assertEqual(dec(), 0)

    def testNonLocalMethod(self):
        def f(x):
            class c:
                def inc(self):
                    nonlocal x
                    x += 1
                    return x
                def dec(self):
                    nonlocal x
                    x -= 1
                    return x
            return c()
        c = f(0)
        self.assertEqual(c.inc(), 1)
        self.assertEqual(c.inc(), 2)
        self.assertEqual(c.dec(), 1)
        self.assertEqual(c.dec(), 0)

    def testGlobalInParallelNestedFunctions(self):
        # A symbol table bug leaked the global statement from one
        # function to other nested functions in the same block.
        # This test verifies that a global statement in the first
        # function does not affect the second function.
        local_ns = {}
        global_ns = {}
        exec("""if 1:
            def f():
                y = 1
                def g():
                    global y
                    return y
                def h():
                    return y + 1
                return g, h
            y = 9
            g, h = f()
            result9 = g()
            result2 = h()
            """, local_ns, global_ns)
        self.assertEqual(2, global_ns["result2"])
        self.assertEqual(9, global_ns["result9"])

    def testNonLocalClass(self):

        def f(x):
            class c:
                nonlocal x
                x += 1
                def get(self):
                    return x
            return c()

        c = f(0)
        self.assertEqual(c.get(), 1)
        self.assertNotIn("x", c.__class__.__dict__)


    def testNonLocalGenerator(self):

        def f(x):
            def g(y):
                nonlocal x
                for i in range(y):
                    x += 1
                    yield x
            return g

        g = f(0)
        self.assertEqual(list(g(5)), [1, 2, 3, 4, 5])

    def testNestedNonLocal(self):

        def f(x):
            def g():
                nonlocal x
                x -= 2
                def h():
                    nonlocal x
                    x += 4
                    return x
                return h
            return g

        g = f(1)
        h = g()
        self.assertEqual(h(), 3)

    def testTopIsNotSignificant(self):
        # See #9997.
        def top(a):
            pass
        def b():
            global a

    def testClassNamespaceOverridesClosure(self):
        # See #17853.
        x = 42
        class X:
            locals()["x"] = 43
            y = x
        self.assertEqual(X.y, 43)
        class X:
            locals()["x"] = 43
            del x
        self.assertFalse(hasattr(X, "x"))
        self.assertEqual(x, 42)

    @cpython_only
    def testCellLeak(self):
        # Issue 17927.
        #
        # The issue was that if self was part of a cycle involving the
        # frame of a method call, *and* the method contained a nested
        # function referencing self, thereby forcing 'self' into a
        # cell, setting self to None would not be enough to break the
        # frame -- the frame had another reference to the instance,
        # which could not be cleared by the code running in the frame
        # (though it will be cleared when the frame is collected).
        # Without the lambda, setting self to None is enough to break
        # the cycle.
        class Tester:
            def dig(self):
                if 0:
                    lambda: self
                try:
                    1/0
                except Exception as exc:
                    self.exc = exc
                self = None  # Break the cycle
        tester = Tester()
        tester.dig()
        ref = weakref.ref(tester)
        del tester
        self.assertIsNone(ref())


def test_main():
    run_unittest(ScopeTests)

if __name__ == '__main__':
    test_main()